Here's a great way to instantly make your shoulder raises (front and side) more efficient and effective: Simply hold a light resistance band and a dumbbell at the same time.
The band allows you to begin the exercise with tension, as opposed to just holding the dumbbells where you'd have almost zero tension when the dumbbells were by your sides.
As you raise your arms away from your body, the mechanical advantage of the bands increases while it decreases on the dumbbell. This creates a sort of "accommodating resistance" effect which causes your shoulders to work harder through the entire range of motion, not just at the top of the movement (when your arms are at 90-degrees with your torso).
All that technical talk aside, it's a great shoulder blaster!